Abstract
There is a high rate of forearm deformity in patients with hereditary multiple exostoses (HME), and a quarter of patients acquire a dislocated radial head due to disproportionate ulnar shortening.
One-hundred and six patients with HME aged 15 years or older were identified from a prospective database. Flexion and extension of the elbow and wrist, and supination and pronation of the forearm was measured. The number of exostoses affecting the proximal and distal radius and ulna were recorded. Proportional ulna length was calculated as a percentage of the patients measured height ([ulna length/height] × 100).
More than 70% of patients were affected by exostoses of the forearm, of which the distal radius was the commonest site to be affected (73%). One in seven patients had a dislocated radial head, which was associated with proportional ulna shortening (p<0.001). Both radial head dislocation (p<0.001) and proportional ulna shortening (p<0.001) were confirmed to be independent predictors of forearm motion on multivariable regression analysis. In conjunction with other predictors these could be used to calculate ROM of the forearm. In addition proportional ulna length was also an independent predictor of radial head dislocation (p<0.001).
Proportional ulna length could be used as a tool to identify patients at risk of diminished forearm motion and radial head dislocation during childhood, who could be monitored clinically and radiographically, and surgical intervention could be offered before deterioration in function and dislocation of the radial head occurs.
